Seasonal Change in Home Blood Pressure Monitoring Is Associated With Renal Outcome and Mortality in Patients With Chronic Kidney Disease

Background: Blood pressure (BP) variation may result in poor cardiovascular and renal outcomes. We investigated the pattern of seasonal BP change and its association with outcomes in patients with chronic kidney disease (CKD) living in southern Taiwan. Methods: We conducted a retrospective analysis of a prospective observational cohort consisting of outpatients with CKD for the period between December 2014 and December 2019. These patients were grouped according to the pattern of seasonal BP variation, namely, consistently higher average systolic BP (>= 8 mmHg) in wintertime than summertime (Group A), consistently lower average systolic BP (>= 8 mmHg) in wintertime than summertime (Group B), large variation of average systolic BP (>= 8 mmHg) without a specific pattern related to weather (Group C), and little fluctuation of average systolic BP (<8 mmHg) throughout the years (Group D). The study endpoints were >= 40% reduction in estimated glomerular filtration rate (eGFR), end stage renal disease (initiation of dialysis or transplantation), or death. Results: We analyzed 507 eligible patients, of whom 17.2% exhibited consistent BP elevation in the wintertime. There were 56.8% of patients conducting regular home BP monitoring. Cox regression analysis showed home BP monitoring was independently associated with better outcome in 507 CKD patients (HR 0.72, 95% CI 0.56-0.94, P = 0.0162). Compared with the other three groups, patients with BP elevation in the wintertime (Group A) were older, had a higher prevalence of diabetic nephropathy and nephrotoxic agent use, a lower prevalence of statin use, higher eGFR decline rate, and a worse outcome. Patients with BP reduction in the wintertime (Group B) were associated with the best outcome. Cox regression analysis indicated that consistent BP elevation in the wintertime in 288 CKD patients with home BP monitoring was significantly associated with a worse composite outcome (i.e., >= 40% reduction in eGFR, end stage renal disease, or death) after adjustment for various confounding factors. Conclusion: Home BP monitoring is crucial, and associated with better outcome in CKD patients. Consistent home BP elevation from summertime to wintertime in patients with CKD was associated with a poorer composite outcome.